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Title: Investigation of the mechanisms of the G2/M phase transition in human cells : the role of Greatwall kinase
Author: Vesely, Clare
ISNI:       0000 0004 2747 5348
Awarding Body: University of Sussex
Current Institution: University of Sussex
Date of Award: 2013
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Understanding the mechanisms and factors that govern cell cycle control is key to developing more effective treatments for human diseases, such as cancer. The human MASTL gene encodes an AGC family kinase, Greatwall kinase, that is conserved among higher eukaryotes. The protein contains an unusual bifurcated kinase domain separated by a stretch of nonconserved amino acids. In Drosophila, mutations in Greatwall cause the failure of chromosomes to condense resulting in a delayed entry in to and progression through mitosis. In mitotic Xenopus egg extracts, immunodepletion of Greatwall results in exit from M phase, characterised by the decondensation of the chromosomes and the reforming of the nuclear envelope. The addition of purified Greatwall to egg extracts immunodepleted for Greatwall causes precocious phosphorylation of Cdc25 and premature entry into mitosis. These reports indicate that Greatwall plays an important role in the control of mitosis but little is known about the function of Greatwall kinase in human cells, its structure, or control of its activity. This project aimed to elucidate the role of this novel kinase in human cells. To this end, the gene has been cloned and antibodies generated to allow the study of human Greatwall kinase. RNAi-mediated knockdown of Greatwall in HeLa cells caused aberrant mitotic progression and apoptosis. To gain further insight into the mechanism of Greatwall activation, the Greatwall kinase structure was modelled and key motifs of the kinase fold identified. In particular, a key activating phosphorylation was identified, and a specific antibody raised to this site, allowing investigation of the regulation of Greatwall activity at mitotic entry and exit. The use of chemical genetics to attempt to specifically inhibit the kinase in human cells is described. Finally, evidence is presented that Greatwall kinase may represent a promising new biomarker and drug target for cancer therapy.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: QH0426 Genetics ; QH0447 Genes. Alleles. Genome ; QH0573 Cytology